Toughness is right below the DPS estimate. This Monk has over 1 million effective HP.
Toughness (also known as Effective HP, or EHP) is one of the three "effectiveness statistics" shown on the main Character Screen of Diablo III, alongside Damage output and Recovery of EHP. It estimates the amount of raw damage an enemy must direct at a character to bring them from full Life to zero HP (i.e. death), and is much larger than the character's actual Life pool due to effects which reduce damage taken. Overall, these effectiveness statistics are designed to give players a quick way to judge the effects of changing items and skills; the percentage change to each of them that would occur is shown whenever a potential new item is hovered on in the Inventory.
Toughness was first shown in the pre-expansion patch 2.0.1.
Contributing stats[]
Toughness is an approximate characteristic, as not all defensive properties are taken into account. It is based on maximum Life, Armor, all resistances, Damage Reduction from skills and Legendary or Set item powers, Dodge chance, and some other modifiers. The resistances are averaged, and not all attacks may be dodged, so actual Toughness varies based on the attack being faced. Some modifiers are not included in the displayed Toughness value at all, such as reduced damage from elites or the guaranteed 30% damage reduction that the Barbarian, Monk, and Crusader classes possess.
Recovery is measured in Toughness units/Effective HP per second. Individual stats may affect them differently:
- Life-increasing bonuses, primarily from Vitality and percentage Life increases, make a character more durable, but reduce the relative impact of healing against the higher life pool.
- Reducing damage taken increases Toughness and Recovery at the same time, since both the initial pool of Life and any Life recovered is harder to lose.
While damage reduction is positive for both aspects, the key idea is that it's multiplicative with total Life, so Toughness suffers increasingly severely without enough Life. Overall, a balance of stats is required for success, with Life, reduced damage taken, and regeneration all supporting each other.
Impact[]
Very low Recovery relative to Toughness may require frequent use of Healing Potions or even trips back to town to recuperate from fights, while very low Toughness relative to Recovery leads to dangerous rapid swings between low and high health during combat. Very low Damage output compared to the defensive stats leads to long fights and slow progress, while very low Toughness leads to "glass cannon" gameplay with a high risk of sudden death. The "required toughness" for any fight varies widely by the player's game style, build, and personal preferences.
In the endgame, using multiple percentage-based Damage Reduction powers is an especially effective way to increase Toughness. They apply multiplicatively with each other and do not suffer from the diminishing returns that would be encountered by stacking even more Armor or Resistance.